1. Technical Field of the Invention
This invention relates to telephone cable splice closures and, in particular, to an adapter for converting a cable closure nozzle to a selectable diameter two cable entrance.
2. Description of the Prior Art
In telecommunications systems multiconductor cables are employed to extend service to a number of customers. Oftentimes the conductors in the cable are encased in a protective outer sheath. These cables must be spliced periodically to connect succeeding portions of cables and to provide access to the cables for branch cables, terminals and the like. At a splice in such cables the protective sheaths must be disturbed. This provides an opportunity for moisture and other environmental elements to reach and destroy the unprotected conductors and splice. Consequently, splice cases have been developed to seal such cable splices.
One example of a cable splice closure suitable for the above purpose is disclosed in C. W. Faust et al, U.S. Pat. No. 3,971,894 issued July 27, 1976. Faust et al disclose apparatus for enclosing splices between two or more multiconductor cables. The apparatus includes a unitary support member which has affixed thereto a cable ground sheath bonding circuit, cable support apparatus and clamps for securing the apparatus to a messenger strand. Completed splice connections are sealed in a unitary flexible weatherproof cover.
While the Faust et al closure represents a significant improvement in the design of cable splice closures, in some instances it is necessary to route two cables through a given closure nozzle. For situations such as this additional measures must be taken to insure a weathertight seal about the two cables. Accordingly, there is a need for some form of adapter to enable this type of entrance to the splice closure to be readily effected.
Some attention heretofore has been directed to a solution of this problem as evidenced by W. H. Channell, U.S. Pat. No. 3,458,649 issued July 29, 1969. Channell discloses a device including a sleeve which is used to house a cable splice. Grommets are provided for each end of the sleeve. These grommets have bushings to afford a method for sealing all cable sizes within the size range of the grommets and the sleeve.
In accordance with the Channell approach, a strip carrying a number of upstanding bushings in spaced apart relationship is provided with the cable splice sleeve. Each of the bushings has a bore which varies as to diameter and all of the bushing bodies have the same external diameters. In practice it is necessary for an installer to select the appropriate bushing whose bore diameter corresponds to the diameter of the cable to be routed into the splice sleeve. While Channell makes some attempt to accommodate various diameter cables within a given splice sleeve, no attention has been directed to the solution of the problem of routing two cables of varying diameters into a single opening in the splice sleeve such that the entry around each of the cables is sealed against environmental elements.
Another example of the effort directed to a solution of this problem appears in G. W. Gillemot et al, U.S. Pat. No. 3,920,886 issued Nov. 18, 1975. Gillemot et al disclose a kit of components for encapsulating a branchout splice to an installed power distribution cable. The kit includes a resilient tubular splice housing having an interlocking portion and slit elastomeric grommets sealing the cable to the housing ends. A sleeve valve encircles the housing and closes a potting compound charging port. Additional slit sleeves serve as adapter grommets for accommodating smaller cable sizes. Although Gillemot et al disclose a method for accommodating two cables, they specifically rely on separate grommets and potting compound to effect an environmental seal about the two cables.
A more recent example of the state of the art of splice closures is evidenced by D. A. Horsma et al, U.S. Pat. No. 4,095,044 issued June 13, 1978. Horsma et al disclose a splice case which includes a shell defining a cavity for enclosing a splice. The shell is longitudinally split and includes openings at the ends along the longitudinal split for receiving incoming cable. A multiple cable adapter of thermally responsive sealant is sized to fit within a cable opening in the splice case and includes a plurality of longitudinally extending channels for accommodation of multiple incoming cables.
Utilization of the Horsma et al approach requires the activation of heaters located within the splice case to simultaneously cause the sealant along the longitudinal split and the adapter to form a seal and preferably an integral bond for the shell and incoming cables. As is clearly illustrated by FIGS. 3 3 through 7 of Horsma et al, accommodation of multiple cables requires a number of individual adapters. Moreover, the selection of a given adapter is limited to a given cable diameter.
In view of the foregoing, it should be evident that a satisfactory solution to the problem of converting a cable closure nozzle to a selectable diameter two cable entrance has not as yet been disclosed.